From the Guidelines
Medications that can affect cardiac conduction, particularly those that prolong the QT interval, should have an EKG performed prior to administration. These include antiarrhythmic drugs like amiodarone, sotalol, and procainamide; certain antibiotics such as macrolides (erythromycin, azithromycin, clarithromycin) and fluoroquinolones (moxifloxacin); antipsychotics like haloperidol and quetiapine; and antidepressants including tricyclics (amitriptyline) and some SSRIs (citalopram) 1. Other medications requiring pre-administration EKGs include digoxin, hydroxychloroquine, methadone, and certain cancer therapies.
Some key points to consider when deciding which medications require an EKG prior to administration include:
- The medication's potential to prolong the QT interval, which can predispose patients to dangerous arrhythmias like Torsades de Pointes
- The patient's pre-existing cardiac conditions, electrolyte abnormalities, or use of multiple QT-prolonging medications, which can increase the risk of cardiac conduction abnormalities
- The need for baseline cardiac measurements, particularly the QT interval, to monitor for developing conduction abnormalities during ongoing therapy
According to the British Thoracic Society guidelines, an ECG should be performed before, and 2 weeks after, starting drugs that are known to prolong the QT interval, such as azithromycin or clarithromycin 1. This highlights the importance of monitoring cardiac conduction in patients taking these medications.
In general, medications that can affect cardiac conduction should be administered with caution, and an EKG should be performed prior to administration to ensure patient safety. This is particularly important for patients with pre-existing cardiac conditions or those taking multiple medications that can affect cardiac conduction.
From the FDA Drug Label
Initiation of Sotalol AF Therapy Step 1. Electrocardiographic assessment: Prior to administration of the first dose, the QT interval must be determined using an average of 5 beats If the baseline QT is greater than 450 msec (JT ≥330 msec if QRS over 100 msec), Sotalol AF is contraindicated.
The medication that would typically require an EKG prior to administration is Sotalol.
- Key points:
- The QT interval must be determined before the first dose.
- The baseline QT interval must be ≤450 msec to start Sotalol AF therapy.
- EKG monitoring is necessary during initiation and titration of Sotalol AF. 2
From the Research
Medications Requiring EKG Prior to Administration
- QT-prolonging drugs, such as haloperidol 3, amiodarone 4, 5, sotalol 5, 6, and quinidine 5, may require an EKG prior to administration to assess the risk of QT interval prolongation.
- Anti-arrhythmic drugs, including dofetilide, procainamide, flecainide 5, can also cause QT prolongation and may necessitate EKG monitoring before initiation of therapy.
Importance of EKG Monitoring
- EKG monitoring is crucial in patients with risk factors for QT prolongation, such as age, sex, and electrolyte imbalances 5.
- Close monitoring of the QT interval is recommended for patients receiving anti-arrhythmic therapy 5.
- The signal-averaged ECG can detect changes in QRS duration and late potential duration induced by antiarrhythmic drugs, such as sotalol 6.
Clinical Practice
- Compliance with recommendations to perform an electrocardiogram when starting a new QT-prolonging drug is extremely low, as seen in the case of haloperidol 3.
- EKG should be considered in patients who have known cardiovascular disease or an increased risk for it, and current ECG tracings should always be compared with previous tracings 7.